What is CONTRACT Testing?
Microservices are becoming popular nowadays in the modern era and one strategy to test microservices is Contract Testing
Contract testing is carried out to confirm that two distinct systems or microservices can function together without issue. These applications are integrated based on the integration context that has already been established.
Simply said, it verifies the seamless communication between two microservices and their integrated interface to satisfy the needs of the larger application of which the microservices are a part.
A contract is created to record and store the interactions between the microservices. This agreement is then periodically validated to make sure that the participating services are successfully complying with or abiding by the terms of integration. Both systems must eventually come to an understanding of how the contract will change over time and decide on the permitted interactions based on updates in accordance with the application’s growth roadmap.
Contract testing looks at each individual connected pair of components and verifies whether each of these pairs is able to communicate according to the specifications (or expectations) at any given point in time. If all consumer-provider pairs are able to communicate with one another, there should not be any issues at the integration level.
The Uncertainty of Integration Testing in a Microservice Architecture?
It is pretty natural to assume that contract testing is, in many ways, similar to integration testing in its principles.
Additionally, the assumption is pretty much true. But what about digital assurance in the cloud and microservices world? For an application with a microservices architecture, it is practically difficult to have a perfect end-to-end integration testing process.
It will be difficult to detect errors or communication problems between specific interdependent microservices once all components have been deployed and tested. In addition, end-to-end integration testing takes time due to the several systems that must operate simultaneously or sequentially based on dependencies. Each test iteration needs data preparation and other preparations, which increases the complexity. Their poor scalability, particularly when a cascade of microservices or systems must be covered under their scope, can make them unreliable over the long term. It becomes challenging to identify and correct the flaws.
The Initiation of Contract Testing
Contract testing evolves from the end-to-end integration approach and leverages a contract to capture all interactions between microservices as necessitated by the application.
The contract is created by the code itself. In order to stay up with changing market or customer expectations, it ensures continual monitoring and upgrades based on the application’s real-time advancements and customisation requirements.. It also ensures that each microservice or system is individually tested from the other for validation of the interaction contract.
Contract testing consists of two types , which are:
Consumer-Driven
Provider-Driven.
In Consumer — driven, the Consumers define their expectations and the Provider checks that they’re fulfilled it . In provider-driven, the Provider defines the contract, and Consumers check that they’re compatible with it.
Consumer-driven contract testing Consumers and producers both have a role in consumer-driven contract testing. Here is when considering testing in microservices becomes important. Here, it makes sure that the provider is in line with what the customer expects. It has been accomplished using either an explicit contract or an implicit contract.
Provider-driven contract testing Contract tests that are created by the dependency’s maintainer are known as provider-driven tests. They function as executable documentation for how the maintainer thinks their library or service should work and are run as a part of the maintainer’s process.
Advantages of Contract Testing
- Faster execution
- Easy Maintenance because it is not necessary to learn and understand the entire system to plan your tests
- Easier Debugging
- Reusability because scripts used for contract testing can be reused again which ultimately saves time in future test scenarios. Each component can be independently tested.
- Bugs can be identified earlier — Contract testing makes it simpler to identify bugs and flaws on developer computers locally. The amount of time and effort required is much less because the testing’s scope is smaller than it would be if end-to-end integration testing called for as many artifacts as possible.
Tools that can be used for Contract Testing
There are many tools available in the market. Few of the popular tools are:
- PACT (www.pact.io) — Pact is an open-source language-agnostic consumer-driven language-agnostic framework with some helpful features. This has faster feedback time.
- Spring Cloud Contract (https://cloud.spring.io/spring-cloud-contract/) — This is a provider driven framework.
- Postman- Consumer driven contact testing can be easily tested using postman
Conclusion
The testing difficulties presented by microservices can be overcome through contract testing. Consumer-driven testing puts the customer in charge. There are a variety of testing tools on the market. The natural and adaptable nature of Postman is thought to make it a good tool.
References
‘How does contract testing work’ will be discussed in the next blog. Stay Tuned!!